The present invention relates to an apparatus for locating leaks in a conventional heat exchanger which has a plurality of tubes mounted at either end in a tube sheet.
A common form of heat exchanger used in industrial applications consists of a cylindrical elongated chamber having a dome-shaped cap or derby head at one end. A plurality of closely spaced elongated tubes are mounted in associated corresponding bores in each of two spaced apart tubes sheets at either end of the vessel. The tubes are open at both ends. At the end of the vessel opposite the derby head there is a header divided into an inlet chamber and an outlet chamber and containing a fluid inlet in the inlet chamber and a fluid outlet in the outlet chamber. The space around the tubes also has a fluid inlet proximate one end of the tubes and a fluid outlet proximate the other end. Fluid is ordinarily pumped into the header inlet, passes through those tubes which communicate with the inlet chamber through to the opposite end proximate the derby head and then flow back to the outlet chamber through those tubes which communicate with the latter. Heat is exchanged with fluid that passes through the central portion of the vessel around the elongated tubes. Consequently, any leaks in the tubes themselves or in the space between the tube sheets and the tubes can result in contamination of the fluids between which heat is being exchanged.
The common procedure for testing for leaks in the tubes includes removing a plate covering the header as well as the derby head and, in succession, plugging each tube at one end and pressurizing it at the other. Any leaks will result in fluid passing out of the fluid inlet for a particular tube having a leak.
In an assembly having 1,000 or more tubes, which is a common type of vessel, such a procedure involves shutting down the heat exchanging system for several days while each tube is tested in succession. Clearly, such a procedure is time-consuming and costly. Moreover, the foregoing procedure is not capable of locating leaks between the tubes sheets and the tubes.